a) Field of the Invention
The present invention is concerned with a positioning device for use on a woodwork table having a circular saw mounted thereon.
More particularly, the invention is concerned with a device specially adapted to properly position and hold a wood piece to be sawn at a proper location on a woodwork table of the above mentioned type, which is commonly called in the trade as a "table saw" or "saw husk".
b) Brief Description of The Prior Art
Using tablesaw which may or not be of the movable type, involves positioning the workpiece to be cut on the table. For this purpose, it is known to provide an abutment or fence against which the workpiece may bear. A problem arises as to how to hold the workpiece in accurate position corresponding to a required length or width for cutting. It is also known to provide stop means against which the workpiece may be leaned to achieve such an accurate position.
For instance, U.S. Pat. No. 751,121 issued on Feb. 2, 1904 to C. H. Tidey discloses a saw table having a plurality of sliding gauges stopped by brackets. The latter are limited to a small number and each gage is secured to its bracket by a set screw. Every time that a worker needs a measurement which is not available from any of the gages, a re-setting is necessary.
U.S. Pat. No. 4,256,000 issued on Mar. 17, 1981 to C. Seidel discloses a table saw including a worktop designed to provide an abutment for a plurality of boards of the same length.
U.S. Pat. No. 4,961,607 issued on Sep. 8, 1987 to F. A. Webb, discloses a positioner which may be located on either side of a radial arm saw. Such positioner is not suited to rapid location of different saw measurements.
U.S. Pat. No. 4,972,949 issued on Nov. 27, 1990 to J. S. Grove, discloses a radial arm saw including a calibrated fence having a plurality of stop gauge members that are slidably mounted in fence units. This construction does not allow for infinitely precise measurements. Also, the stop gauge members are spring-loaded and therefore prone to wearing out and breakage.
The follow U.S. patents are also of interest in this very particular field:
U.S. Pat. No. 957,782 issued on May 10, 1910 to J. M. Leaver et al
U.S. Pat. No. 2,485,274 issued on Oct. 18, 1949 to R. G. Garret; and
U.S. Pat. No. 4,946,149 issued on Aug. 7, 1990 to D. G. Greene.
In general, most of the table saws presently available in the trade, like the one sold by the german company HOLZ-HER, are provided with a calibrated abutment beam which is mounted onto the worktable so as to extend transversally to the sawing direction. A screwable stop member is adjustably displacable along the beam and has an element which serves as a stop for the workpiece, so that the latter does not slip or otherwise move on the worktable transversally away from the saw during the sawing action. The stop must be manually positioned along the beam according to the desired dimension of the workpiece for each cutting operation.
This basic structure is quite efficient. However, a significant difficulty arises when one wants to saw a plurality of boards, panels and the like at one time. The workpieces may be required to be of the same or different dimensions, or a combination of both. Thus, for each piece to be worked, the stop member has to be unscrewed, positioned anew and re-tightened. This, of course is non-productive, time-consuming and a source of error.